Iodine is a micronutrient critical for normal human development and thyroid function. Iodine deficiency occurs in geographic areas that lack iodine in the soil and water as a result of geologic activity. Many such areas are found worldwide and approximately 30% of the world's population, in 130 countries across the globe, live in iodine deficient areas.
Health problems associated with deficient iodine intake are known collectively as iodine deficiency disorders (IDD). These disorders range from goiters and mild neurologic deficiencies to overt mental and physician retardation and cretinism. Iodine deficiency remains the leading cause of preventable mental retardation worldwide.
Preventing IDD is straightforward. Supplementing iodine intake into the diet of people living in areas of endemic iodine deficiency can successfully prevent IDD. Iodinization of salt is an inexpensive and commonly used method to increase iodine intake in a community. Despite the effectiveness and low cost of this intervention, millions remain at risk for IDD because they lack access to iodize salt, the available salt is inadequately iodized or they do not ingest the iodized salt. Therefore, periodic monitoring of the dietary iodine intake is important. Additional information concerning IDD can be found in the references cited below, all of which are incorporated herein by reference.
In view of the above, periodic testing and monitoring for iodine deficiency could be beneficial. The current standard for assessing iodine deficiency is measurement of urinary iodine. Measuring urine iodine is a standardized laboratory test, which utilizes the oxidative-reductive capacity of iodine, which subsequently catalyzes a color reaction. Although relatively simple to do in a laboratory, the testing is not conducive to rapid, individual point of care testing. Point of care iodine deficiency testing that is simple and permits individuals or small clinics to assess the iodine status at any time is required. If iodine status is determined to be low, communities and individuals will be motivated to take advantage of sources of iodine including iodized salt.
Iodine is stored in the thyroid, breast and salivary glands. Of these, the salivary glands are a useful source of material for detecting the iodine level in a subject given the ease of access to saliva, the inorganic form of iodine in saliva and because the release of iodine from the salivary gland is not affected by plasma iodine levels. However, attempts to quantitate iodide in salvia using iodide binding moieties have been problematic because the presence of other salivary halides interferes with the assay.